GRAAF GAAFiti WFB ONE - Schematic needed - diyAudio
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Old 20th November 2011, 01:48 PM   #1
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Default GRAAF GAAFiti WFB ONE - Schematic needed

Who can post the schematic of this GRAAFiti preamp?
GRAAFiti WFB ONE Preamplificatore Valvolare
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Old 29th March 2013, 11:36 AM   #2
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schematic still needed. There are large issues by the phono input particularly with noise.
No difference in noise between open input and closed input in the "MC" mode. Closed input means with present plug-in socket (cynch connector) from lyra cartridge.
Who can upload a schematic diagram?
Graaf and audio excellence in Germany don't release any schematic.
Thank you for your efforts.
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Old 19th May 2013, 02:27 PM   #3
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type referencing brings no informations in this case. Go to new thread
PC900/4AH5
PC900 / EC900 curves
in context to the circuit description of the input stage in front of the riaa stages
Pre-Amp with Phono needs new tubes (Schaltungsbeschreibung)
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Old 20th May 2013, 02:41 PM   #4
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Default Own schematic draw from the Phono Stage now present

Check out the schematic - maybe several errors are present because I haven't access to PCB's solder side. Particularly the connections of the potentiometers for the gain adjust so as C07L (47uF/100V) are unknown, because the copper wires are not reach from component side. The circuit description don't correspondend with the actually circuit because the caims from the circuit description are untrue (first "without Feedback" and secondly "SRPP")
Attached Images
File Type: jpg Graaf_WFB One_Phono.jpg (406.7 KB, 368 views)
File Type: jpg GRAAF-WFB-ONE-circuit describtion.jpg (259.5 KB, 351 views)
File Type: jpg Graaf_WFB One_Heizung.jpg (132.6 KB, 320 views)

Last edited by tiefbassuebertr; 20th May 2013 at 02:56 PM.
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Old 20th August 2013, 07:39 PM   #5
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Now I have access to PCB's solder side. There are two faults in my drawing from first image in my previous post:
1) C07L (47uF/100V) must be in parallel to C06L resp R16L
2) in the connection between R12L/C05L and grid V03L (PIN7 of E88CC/6922) must be introduce a serial resistor of 1K (R15L) and between R12L/C05L and GND must be introduce a resistor of 510K (R14L).

The noise of the MC input is too large - additional there isn't the usual noise reduction in case of shorted input resp. fit in the RCA-plugs from turntable.

Last edited by tiefbassuebertr; 20th August 2013 at 07:43 PM.
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Old 1st September 2013, 09:54 PM   #6
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images from bottom view after create a removable plate to reach the solder side without completely disassemble.
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File Type: jpg Graaf WFB Bottom view DSCN0111.jpg (481.3 KB, 212 views)
File Type: jpg Graaf WFB Bottom view DSCN0113.jpg (491.7 KB, 195 views)
File Type: jpg Graaf WFB Bottom view DSCN0117.JPG (563.4 KB, 100 views)
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Old 10th October 2013, 08:09 AM   #7
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I am looking for the National version of this tubes (4AH5).
Who know, where I can order this tubes?
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Old 2nd November 2013, 02:09 PM   #8
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new schematic created in circuitmaker as PDF file
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